What is DNA?

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What is DNA?

• Instructions for making proteins
• Blueprint for who we are
• Where is it found?
• Found in the nucleus
• What does DNA stand for?
• Deoxyribonucleic Acid

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The Structure of DNA

• Double helix
• Structure of DNA Twisted Ladder

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Who Discovered DNAs Structure?

• SCANDAL! Read all about it!
• Rosalind Franklin, James Watson, Francis Crick,
  Maurice Wilkins discovered the shape (double
  helix) of DNA is 1953.

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THINK!

• DNA is a polymer of Nucleotides.
• What are the 3 parts of a nucleotide?

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Nucleotides

• DNA Subunit
• 3 components
• a sugar
• a phosphate group
• a nitrogen base

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(No Transcript)
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Nitrogen Bases

• 4 Types
• Adenine
• Thymine
• Guanine
• Cytosine
• REMEMBER
• At The Golf Course

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Complementary Base Pairs

• Nitrogen bases always pair with the same partner
• Hydrogen bonds hold the bases together.
• A--T (At--The)
• G--C (Golf--Course)

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THINK!

• What would the complementary strand be?
• A-T-C-C-G-T-T-T-A-C-A-G-G-A

T-A-G-G-C-A-A-A-T-G-T-C-C-T
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DNA Review
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DNA is the instructions for making what?
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Protein
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What type of biomolecule is DNA?
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Nucleic Acid
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What type of sugar is in DNA?
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Deoxyribose or pentose
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Draw and name the shape of dna
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Double Helix
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Who took credit for discovering dna?
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Watson and Crick
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Who actually discovered dna?
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Rosalind Franklin
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What is a polymer?
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A long chain of repeating units (subunits)
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What is the subunit of DNA?
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Nucleotide
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Sugar, phosphate and ___________ make up a
nucleotide.
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Nitrogen Base
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Adenine, ________, cytosine, and __________ are
the 4 nitrogen bases of dna
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Thymine and guanine
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Thymine pairs with ___________
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Guanine pairs with __________
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Write the complimentary standC G T A
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G - C A T
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Write the complimentary strandg g t a
t a
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Write the complimentary stranda a t g c
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Write the complimentary strandc t a t
g
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How DNA Strands Form

• Nucleotides join to form long chain (polymer)
• Sides of the ladder
• Sugar Phosphate
• Rungs of ladder
• Nitrogen bases bond together

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How is DNA Organized?

• Histone proteins act like spools that wind up DNA
  to keep it organized.

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During Interphase

• How does DNA exist?

Unwound! (Chromatin)
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Why Chromatin?

• What happens during Interphase?
• DNA Replicates!
• DNA is uncoiled so that enzymes can unzip it.
• When it is unzipped, DNA can be duplicated.

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DNA Replication

• Process by which DNA is copied
• Occurs before mitosis and meiosis (during
  interphase!)

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How DNA Duplication Occurs

• Step 1 The Helicase enzyme unzips the DNA strand

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• Step 2 The DNA Polymerase enzyme attaches free
  floating nucleotides to the exposed nitrogen bases

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Result 2 Complete Strands!
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Replication Fork
DNA Polymerase
Original Strand
Helicase
New Strand
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• Semiconservative Replication one of the original
  strands is present in each new strand of DNA.

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The Central Dogma

• DNA RNA Proteins